When two DC voltage networks are connected, an energy flow may alternatively be needed in both directions. Thus, for example, in motor vehicles, in addition to the existing 14 V network, a 42 V network is introduced in order to be able to supply further loads with higher power demands. Depending on the operating state, it may be necessary to transfer energy from the 14 V network into the 42 V network or vice versa. For this purpose, in each case a DC/DC converter is intrinsically necessary, for which various circuit principles are known, for example the so-called parallel-fed push-pull converter.
These converters operate in push-pull operation on the primary and secondary side, and are distinguished by a good efficiency and simple driving of the semiconductor switches. On the secondary side, rectification is carried out in push-pull by means of two diodes which are connected to the ends of the windings and operate on an L/C filter element.
However, these known converters have the disadvantage of being usable in each case only in one direction of action (energy transfer direction), so that two of the known DC/DC converters are needed in order to connect the DC voltage networks.